• Computers and Concrete
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• v.27 no.3
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• pp.225-239
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• 2021

Carbon fiber reinforced polymer (CFRP) has extensive use in strengthening reinforced concrete structures due to its high strength and elastic modulus, low weight, fast and easy application, and excellent durability performance. Many studies have been carried out to determine the performance of the CFRP confined concrete cylinder. Although studies about the prediction of confined compressive strength using ANN are in the literature, the insufficiency of the studies to predict the strain of confined concrete cylinder using ANN, which is the most appropriate analysis method for nonlinear and complex problems, draws attention. Therefore, to predict both strengths and also strain values, two different ANNs were created using an extensive experimental database. The strength and strain networks were evaluated with the statistical parameters of correlation coefficients (R2), root mean square error (RMSE), and mean absolute error (MAE). The estimated values were found to be close to the experimental results. Mathematical equations to predict the strength and strain values were derived using networks prepared for convenience in engineering applications. The sensitivity analysis of mathematical models was performed by considering the inputs with the highest importance factors. Considering the limit values obtained from the sensitivity analysis of the parameters, the performances of the proposed models were evaluated by using the test data determined from the experimental database. Model performances were evaluated comparatively with other analytical models most commonly used in the literature, and it was found that the closest results to experimental data were obtained from the proposed strength and strain models.

• Journal of the Korean Ceramic Society
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• v.29 no.4
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• pp.312-318
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• 1992

Two kinds of alumina specimens with different grain size (1 and 51 $\mu\textrm{m}$) but same density were prepared by hot-pressing. Fracture strength and fracture toughness of these specimens at low strain rate, sonic velocity, and elastic property were evaluated. Ballistic performance against Cal. 50 AP projectile was characterized by thick-backing method by using A16061-T6 reference block. Mechanical properties measured at low strain rate showed that the specimen with samll grain (SG) were better than specimen with large grain (LG). Fracture strength and fracture toughness of LG specimen were 131 MPa and 3.01 MPa{{{{ SQRT { m} }}, but those of SG specimen were 349 and 4.23, respectively. Sonic velocity and elastic properties of these specimen were similar, but bulk velocity and bulk modulus were different at amount of 4 and 9%. The tendency of ballistic performance was not consistent with the mechnaical properties at low strain rate. The ballistic performance based on quantitative efficiency revealed that the LG specimen (5.13) was ballistically better than the SG specimen (4.00) in spite of their lower mechanical properties.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.934-937
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• 2007

This study focused on investigating the effect of aligned cellulose fibers to the performance of EAPap actuator. The performance of EAPap is dependant on the material direction of cellulose film. Electrospinning was used to improve material directionality of EAPap. DMAc cellulose solution which cotton pulp was resolved in DMAc solvent was used for electrospinning cellulose film. To increase directionality of nano fibers, the Electrospun film was stretched by 10 % strain during drying process. Induced in-plane strain of Electrospun EAPap was proportional to the applied voltage and larger than that of spincast EAPap. It is concluded that the performance of EAPap was improved by aligning cellulose fibers.

• Journal of the Earthquake Engineering Society of Korea
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• v.23 no.3
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• pp.169-181
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• 2019

Seismic performance of ordinary reinforced concrete shear wall systems commonly used in high-rise residential buildings is evaluated. Three types of shear walls exceeding 60m in height are designed by performance-based seismic design. Then, incremental dynamic analysis is performed collapse probability is assessed in accordance with the procedure of FEMA P695. As a result, story drift, plastic rotation, and compressive strain are observed to be major failure modes, but shear failure occur little. Collapse probability and collapse margin ratio of performance groups do not meet requirement of FEMA P695. It is observed that critical wall elements fail due to excessive compressive strain. Therefore, the compressive strain of concrete at the boundary area of the shear wall needs to be evaluated with more conservative acceptance criteria.

• Korean Journal of Agricultural Science
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• v.45 no.4
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• pp.687-694
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• 2018

This study was conducted to investigate the laying performance of six strains of Korean domestic chickens (KDC 1A, 2A, 3A, 1B, 2B and 3B). A total of 288 20-week-old KDC hens were allocated in a completely randomized design to give 12 replicates per each strain (4 chickens per pen). The chickens were fed commercial diets (i.e., week 20 - 32, crude protein [CP] 18.0% and metabolizable energy [ME] 2,850 kcal/kg; week 32 - 40, CP 17.0% and ME 2,800 kcal/kg) ad libitum together with fresh water during the 20-week experiment. Body weight, age of sexual maturity, egg weight, hen-day egg production (HDP) and feed conversion ratio (FCR) were measured during the experiment period (week 20 - 40). Our results show that strain 3B had an improved (p < 0.05) HDP and FCR compared with the other strains on week 24 - 28. However, strain 3A had an improved (p < 0.05) HDP and FCR compared to the other strains on week 28 - 40. Similarly, strain 3A had a higher egg weight (p < 0.05) compared to the other strains on week 28, 32 and 40. In conclusion, the higher laying performance of strain 3A indicates its potential in the development of a KDC strain with improved commercial laying performance.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.3
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• pp.39-43
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• 2010

The main objective of this research is to develop a mechanistic performance predictive model for fatigue cracking of asphalt-aggregate mixtures. Controlled-stress diametral fatigue tests were performed to characterize fatigue cracking of asphalt-aggregate mixtures. Performance prediction model for fatigue cracking was developed using the internal damage ratio (IDR) growth method. In the IDR growth method, the general concepts of the dissipated energy, the reference tensile strain, the threshold tensile strain, and the strain shift factor were introduced. The source of the dissipated energy in the fatigue test is from the intrinsic viscoelastic material property of an asphalt concrete mixture and the damage growth within the asphalt concrete specimen. In controlled-stress mode test, the dissipated energy is gradually increased with an increasing number of load applications.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.644-655
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• 2008

Conventional hyperbolic model does not satisfactorily predict the overall stress-strain behaviors of various geomaterials. Tatsuoka and Shibuya(1992) suggest the generalized hyperbolic equation(GHE) considering strain dependency and calculated performance is in good agreement with precise triaxial compression test results of stress-strain relations over wide range of strains before peak stress condition in some cases, but GHE model also does not satisfactorily predict stress-strain relations as strain goes on state of peak stress in most cases. For improve a weak point of the GHE, in this study, modified form of generalized hyperbolic equation (MGHE model) is proposed which can predict highly nonlinear stress-strain behavior for various geomaterials from small strain to peak stress condition.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.12
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• pp.1645-1656
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• 2010

This study was conducted to investigate the effects of strain on broiler performance, and age at slaughter and postchilling (PC) aging time on meat quality traits. A total of 500 one-day-old chicks (250 Hubbard classic and 250 Lohman) were reared under commercial conditions. Half of the broiler birds from each strain were slaughtered at 32 days and the other half at 42 days old. At each processing day, 168 carcasses were randomly selected (84 Hubbard and 84 Lohman) and divided into groups of 28 carcasses within each strain, and aged for 0, 4 and 24 h after chilling. Average weekly body weight was comparable between strains. Feed conversion ratio was higher (p<0.05) for the Hubbard strain during the second and third week of age. Initial carcass pH was significantly (p<0.05) affected by age where younger birds (32-d-old) had lower pH values than older (41-d-old) birds. Breast temperature was higher (p<0.001) for Lohman than Hubbard at 0, 2 and 4 h of PC. Younger birds had a lower breast temperature (p<0.001) at all measured times of PC. Thaw loss, cook loss and water holding capacity were not significantly affected by strain, age or aging time. Lohman strain had more tender meat (p<0.05) than Hubbard strain, and tenderness was improved with the increase of broiler age and aging time. Meats from Hubbard were lighter and less red than those from Lohman strain where younger birds had darker color. In conclusion, strain, age at slaughter and PC aging duration are critical to breast meat quality characteristics, and 4 h of aging are required before deboning in order to obtain more tender fillets.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.4
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• pp.391-398
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• 2010

In this paper, we propose a sensor design by using a polysilicon strain gauge bonded to a metal diaphragm. The fabrication process of the thin polysilicon strain gauges having thicknesses of $50\;{\mu}m$ was established using conventional MEMS technologies; further, the technique of glass frit bonding of the polysilicon strain gauge to the stainless steel diaphragm was established. Performance of the polysilicon strain gauge bonded to the metal cantilever beam was evaluated. The gauge factor, temperature coefficient of resistance (TCR), nonlinearity, and hysteresis of the polysilicon strain gauge were measured. The results demonstrate that the resistance increases linearly with tensile stress, while it decreases with compressive stress. The value of the gauge factor, which represents the sensitivity of strain gauges, is 34.0; this value is about 7.15 times higher than the gauge factor of a metal-foil strain gauge. The resistance of the polysilicon strain gauge decreases linearly with an increase in the temperature, and TCR is $-328\;ppm/^{\circ}C$. Further, nonlinearity and hysteresis are 0.21 % FS and 0.17 % FS, respectively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.6
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• pp.925-932
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• 1997

Two shear-flexible curved axisymmetric shell elements with two nodes, LCCS(linear curvature and constant strain) and CCCS(constant curvature and constant strain) are designed based on the assumed meridional strain fields and shallow shell geometry. At the element level, meridional curvature, membrane strain and shear strain fields are assumed by using polynomials and the displacement fields are obtained by integrating the assumed strain fields along the shallowly curved meridian. The formulated elements have high order displacement fields consistent with the strain field. Several test problems are given to demonstrate the performance of the two elements. Analysis results obtained reveal that the elements are very accurate in the displacement and the stress predictions.